[EN] The proper maintenance of potassium homeostasis is crucial for cell viability. Among the major determinants of potassium uptake in the model organism Saccharomyces cerevisiae are the Trk1 high affinity potassium ...[+]

[EN] The proper maintenance of potassium homeostasis is crucial for cell viability. Among the major determinants of potassium uptake in the model organism Saccharomyces cerevisiae are the Trk1 high affinity potassium transporter and the functionally redundant Hal4 (Sat4) and Hal5 protein kinases. These kinases are required for the plasma membrane
accumulation of not only Trk1, but also several nutrient permeases. Here, we show that overexpression of the Target of Rapamycin Complex 1 (TORC1) effector NPR1 improves hal4 hal5 growth defects by stabilizing nutrient permeases at the plasma membrane. We subsequently found that internal potassium levels and TORC1 activity are linked. Specifically, growth under limiting potassium alters the activities of Npr1 and another TORC1
effector kinase, Sch9; hal4 hal5 and trk1 trk2 mutants display hypersensitivity to rapamycin; and, reciprocally, TORC1 inhibition reduces potassium accumulation. Our results demonstrate that in addition to carbon and nitrogen, TORC1 also responds to and regulates potassium fluxes.[-]

This work was supported by Spanish Ministry of Science and Innovation (Madrid, Spain) Grant BFU2011-30197-C03-03 (to L. Y.). The authors declare that they have no conflicts of interest with the contents of this ...[+]

This work was supported by Spanish Ministry of Science and Innovation (Madrid, Spain) Grant BFU2011-30197-C03-03 (to L. Y.). The authors declare that they have no conflicts of interest with the contents of this article.
Supported by a pre-doctoral fellowship from the Spanish Research Council (Consejo Superior de Investigaciones Cientificas).
Supported by the Swiss National Science Foundation, the European Research Council, and the Canton of Geneva.[-]